Bi-allelic variants in RNF170 are associated with hereditary spastic paraplegia.

Area of Science:

• Neuroscience
• Genetics
• Cell Biology

Background:

• Calcium (Ca2+) homeostasis is crucial for neuronal function and its disruption is linked to neurodegenerative diseases.
• Inositol 1,4,5-trisphosphate receptors (ITPRs) regulate Ca2+ release from the endoplasmic reticulum and are degraded via the ER-associated degradation pathway.
• Mutations in ITPR1, ERLIN1, and ERLIN2 are associated with hereditary spastic paraplegia (HSP) and cerebellar ataxia.

Purpose of the Study:

• To investigate the genetic basis of autosomal recessive HSP in four families.
• To identify novel genes involved in hereditary spastic paraplegia and cerebellar ataxia.
• To elucidate the role of RNF170 in the degradation of inositol 1,4,5-trisphosphate receptors and its link to neurodegeneration.

Main Methods:

• Genetic analysis of four unrelated families with autosomal recessive HSP.
• Functional evaluation of mutations in patient fibroblasts and SH-SY5Y cells.
• Gene knockdown studies in zebrafish to assess the impact of RNF170 mutations.

Main Results:

• Mutations in the ubiquitin E3 ligase gene RNF170 were identified as the likely cause of autosomal recessive HSP in the studied families.
• RNF170 targets inositol 1,4,5-trisphosphate receptors for degradation, and its mutations impair this process.
• Functional studies confirmed the deleterious effects of RNF170 mutations on cellular calcium homeostasis and neuronal function.

Conclusions:

• RNF170 mutations are a novel cause of autosomal recessive hereditary spastic paraplegia.
• Inositol 1,4,5-trisphosphate signaling pathway is a critical player in hereditary spastic paraplegias and cerebellar ataxias.
• Targeting the inositol 1,4,5-trisphosphate pathway offers a promising therapeutic strategy for these neurodegenerative disorders.